Drilling and blasting of the 3.9km tunnel started from both directions in 1984. What I found astounding was that the opposing drilling heads met half way only 3mm out of alignment. The tunnel was finished in April 1988, four years after construction was started.
Whenever driving through this tunnel I feel a little like a Formula 1 driver speeding though the tunnel at Monaco - it's unfortunate that the speed limit is set at 90km/h :(.